The present invention relates to a BGA (Ball Grid Array) package-type semiconductor device using a TAB (TApe Bonding) tape and a method of manufacturing the same.
As one of the package structures for semiconductor devices, a Tape-BGA package-type semiconductor device (to be referred to as a BGA package hereinafter) is known.
For example, as shown in FIG. 8, this BGA package 1 has a semiconductor chip 2 and a TAB tape 3 having inner leads 4 to be connected to electrodes 2a of the semiconductor chip 2 by inner lead bonding.
A metal (e.g., a Cu alloy) stiffener 5 and a heat dissipation plate 6 formed of a metal plate member (e.g., a Cu alloy member) are stacked on the lower surface of the TAB tape 3. The stiffener 5 is formed into a frame to correct the warp of the TAB tape 3, thereby maintaining the flatness thereof. The heat dissipation plate 6 is called a heat spreader (H/SP) for dissipating heat generated by the semiconductor chip 2. In FIG. 8, a chip mounting portion 6a is formed at the center of the surface of the heat dissipation plate 6 having an entirely rectangular shape. The stiffener 5 forms a frame having an opening that surrounds the chip mounting portion 6a.
In the BGA package 1 described above, as shown in FIGS. 9 and 10, the inner leads 4 of the TAB tape 3 are bonded to the electrodes 2a of the semiconductor chip 2, and the stiffener 5 is adhered to the lower surface of the TAB tape 3 with an adhesive 8 to maintain the flatness thereof. After that, the bonding portions of the electrodes 2a of the semiconductor chip 2 and the inner leads 4 are coated with a resin 9. Solder balls 10 are formed at portions of the surface of the TAB tape 3 described above which correspond to the respective leads.
The heat dissipation plate 6 is set to oppose the lower surfaces of the semiconductor chip 2 and stiffener 5. The semiconductor chip 2 and stiffener 5 are pressed against the heat dissipation plate 6 through a conductive paste 11 such as Ag paste and an adhesive 12, respectively, so that the semiconductor chip 2, stiffener 5, and heat dissipation plate 6 are integrally adhered to each other.
In the conventional BGA package 1 described above, since the frame-like stiffener 5 is formed of a metal plate material made of a Cu alloy or the like, the weight of the whole package increases, and demands for a smaller size and smaller weight cannot be satisfied. If such a BGA package 1 is relatively heavy, when the solder balls (solder bumps) 10 are fused when packaging the BGA package 1, they cannot withstand the weight of the BGA package 1 but are crushed flat to form bridges connected to the adjacent solder balls 10. If the BGA package 1 is heavy, a bonding strength that can withstand a drop impact test for the package cannot be obtained in design.
In the conventional BGA package 1 described above, since the heat dissipation plate 6 and stiffener 5 are formed of metal plate members, the package weight increases, as described above. In addition, the material cost per product increases.
In the BGA package 1 having the above structure, after the stiffener 5 and TAB tape 3 are adhered to each other with the adhesive 8, the semiconductor chip 2 and stiffener 5 are adhered to the heat dissipation plate 6 with the conductive paste 11 and adhesive 12, respectively, resulting in the two adhering steps. As these separate adhering steps are required, the manufacturing process becomes complicated, and the production efficiency is poor.
When the stiffener 5 and heat dissipation plate 6 are fixed to each other by adhesion in this manner, the precision may be degraded due to a positional shift occurring during adhesion. Also, the adhering steps described above take a long hardening time until the adhesives harden, degrading the productivity.
In the BGA package 1 described above, the metal stiffener 5 is adhered to the TAB tape 3. As an excessively large difference is present in thermal expansion between the stiffener 5 and TAB tape 3, during the manufacture or during mounting this package onto a printed circuit board, a stress remains between the solder balls 10 and the mounting board. Then, the long-term reliability decreases.